Manufacture of seat-pillar stays and chain-stays of cycle-frames.



y G. s. JAMES. MANUFACTURE 0F SEAT PILLAH STAYS AND CHAIN STAYS OF CYCLE FRAMES.

APPLICATION FILED OCT. 23. |911- Patented J uly 1, 1919.

III IIII III-II I i GEORGE STEWART JAMES, or BIRMINGHAM, ENGLAND.

j ',MANUFAGTURE orfsEAT-PILLAR Vs'rnvs AND CHAIN-STAYS or CYCLE-FRAMES.

Specification of Letters Patent.

Patented July 1, 1919.

i Application led October 23, 1917. Serial No. 198,118.

To all whom t may concern Be it known that I, GEORGE STEWART JAMES, subject of the Kin of Great Britain, residing at 36 and 37 shted Row, Birmingham, in the county of Warwick, England, have invented certain new and useful Improvements in the Manufacture of Seat- Pillar Stays and Chain Stays of Cycle- Frames, of which the following is a specification. The invention relates to the shaping in a tube length of a cranked or like part such as provided in a seat pillar stay or a chain stay of a cycle frame lfor the purpose of forming the wheel forks.

Said cranked part is usually shaped between press or other tools while the tubular piecev is internallyloaded with resin or the like which needs to be melted out after the shaping demanding subsequent cleaning and trimming operations upon the tube length consequent upon the use of the loading material.

The invention provides a process for the purpose in which thecranked part of the j tube length is shaped between suitable shaping tools while internally supported by two mandrels inserted into the tube one from each end to take up a position close together without overlapping. Said mandrels are cross sectionally shaped to the cross section of the tube, as for example, D shape if the tube is D shape or one D shape and the other circular if the parts of the tube each side the cranking are of such shapes, as for instance in the case of a chain stay. The formation of a curved cranking similar to an ogee curve is primarily the object of the invention in which case the mandrels at their activeends are shaped on their one sides to the curving as will be hereinafter described.

' Fig. 3 is a cross section of Fig. 1 on the i 'dotted linen- A.

'a cranked tube length of dissimilar cross sections each side the cranking and showing the mandrels in position.

Fig. 6 is a cross section of Fig. 5 on the dotted line B-B.

Fig. 7 is a cross section of Fig. 5 on the dotted line C-C.

With reference to Figs. l .to 4 a is a length of D sectioned tube in which the ordinary curved cranking a2 is to be shaped, said tube length Ibeing suitable for a seat pillar stay for a cycle. Two mandrels c and d are inserted into the tube one from each end while the tube length is straight7 as in Fig. 2, to take up positions quite close together without overlapping in anyway at that part of the tube to be cranked. To' position these mandrels they are pushed'into the tube up to stops c2 Z2 behind which latter is a handle c3. vThe carrier e for the mandrel d is immovable longitudinally but permits of said mandrel rising and falling slightly and slightly swinging about the pivot e2 and this carrier is conveniently placed to a pair of dies f and g operated by a press or in any other suitable manner and which are shaped to form the cavity L to .the longitudinal and cross shapes of the tube and cranking as clearly shown by Figs.1,2 and 3. The cavity /L of each tool is in the forni of a semi-circular depression, the remaining portion of the working face of the tool being horizontally flat, each cavity extending across the tool a distance greater than one half the length of the tool and having its inner terminal in the form of a compound curved incline trending toward the flat face of the tool. Moreover, the cavities of the adjacent tools f and g are in relatively reversed positions, so that length a ispushed over the mandrel rl up to the stop Z2 and then the mandrel c is pushed into said tube length from its other end, after which the two dies f and g are brought together to shape the cranking either by one or' two blows from a press, drop stamp, or the like.

It will be clear from the drawings .that the mandrels 0 and d are cross sectionally shaped to the tube and longitudinally shaped at their active ends by suitable curvings 04 d4 which support the tube length oppositely during the, curved cranking of it, Fig. l showing clearly how said active ends operate in the shaping of the cranking.

After the cranking has been shaped the tools are -separated and fboth mandrels 0 and CZ are withdrawn Vone from each end of the tube length.

With reference to Figs. 5 to 7 relating to the curvedcranking of a chain stay the tube length a is at c' of circular cross section and at y' ofy D cross section and it is preferable to shape thestraight length of tu'be to these two cross sections prior to the curved cranking process aforesaid although said cross sectional shaping may be performed from around to D at the portion y" during the curved cranking process. Themandrels c and l are shown within the tube length prior to being withdrawn.

The foregoing method or process of curved cranking is most eective being cheaper to carry out than the resin or like loading method and particularly advantageous inasmuch as it leaves the tube at the cranked part stronger than is the case if cranked while resinloaded for the reason that the metal of the tube is free to stretch and flow throughout the wholel process of shaping the curved cranking.

Having now described my invention what I claim and Vdesire tol secure by Letters Patent is Means for forming and shaping a bend or crank in a tube length comprising complemental external shaping dies arranged one over the other, each having a horizontally flat-face anda semi-circular cavity extending lengthwise thereof a short distance beyond one-half of the length of the` die, each of said cavities having its inner terminal in- Clined in compound `curved form, said cavities being reversely larranged and each7 for a greater portion of its length, being opposite to a portion of the horizontally flat face of the opposing die, and two mandrels insertible within the ltube to be bent and having inner solid ends corresponding in crosssectional contour to and of less dimensions than the cavities of the dies and having innercurved blunt ends, the mandrels vbeing provided with flexible shanks extending from the outer ends thereof, the heads of said mandrels adapted 'to be arranged in reverse positions in the tube to be cranked or bent with their inner curved ends `close together and respectively opposite the inner curved terminals of the cavities in the dies.Y

In ytestimony whereof I have hereunto set my hand in presence of two subscribing witnesses.

GEORGE STEWART JAMES. Witnesses:

GEO. T. FUERY, D. LEAKER.

Copies-of this patent maybe obtained for ve cents each, lby addressing the ,Commissoner of Patents,

' Washington, ID. C. 

